1. Field of the Invention
The invention relates generally to supply of electrical power to pumps and other electrical equipment during drilling and production operations.
2. Background of the Invention
Electrical power is necessary for operating various devices and equipment associated with a subsea well during drilling operations. For example, sensors are typically placed at the wellhead so that operators can monitor the pressures and temperatures. If dual gradient drilling is employed, a subsea pump may be utilized to pump drilling fluid from the well and fluids to the surface. Typically, these devices require different voltages and may require different types of current (e.g., direct current or alternating current). Therefore, during drilling operations dedicated power lines are supply power to these pieces of subsea equipment from the surface. After drilling operations, the mud pump and sensors for drilling purposes are typically removed and other equipment is placed in or near the subsea well for production operations. Sometimes a drilling control pod is landed adjacent the subsea well being drilled, which can supply electrical power to some of the equipment.
Electrical power is also necessary for operating various devices and equipment associated with a subsea wellhead assembly during production operations. A downhole pump may be used. Also, a booster pump may be placed near the wellhead assembly for pumping well fluids (i.e., water and oil with some gas) to the surface or to a subsea collection facility which in turn pumps the well fluids to the surface. Operators also are developing systems placed subsea for processing the well fluids subsea, for the removal of water from the well fluids. Separating the oil from the water in the well fluids allows the operator to pump only the oil to the surface or the collection facility.
Sensors are typically placed at various locations of processing systems for monitoring quantities such as pressures, and flowrates. Like the sensors positioned in the well during drilling operations, sensors on the processing system will typically require a supply of electrical power. Additionally, the pumps for pumping the oil removed from the well fluid will also require a supply of electrical power. Separating the oil in a subsea separator system may be done with separators utilizing electricity to help separate water from the oil in the well fluid. Typically, the voltage and currents of the electrical power necessary for the sensors, separators, and pump in the processing equipment to operate are different. Therefore, in the past, a dedicated supply line must be provided to each of the devices from the surface.